A photosensitive composition, which comprises (A) a compound capable of generating an organic acid represented by formula (I) upon irradiation with actinic ray or radiation: ##STR00001## wherein Z represents a monovalent organic group, when two Z's are present, the two Z's may be the same or different, and they may be bonded to each other to form a cyclic structure; X represents --CO-- or --SO.sub.2--, when two X's are present, the two X's may be the same or different; R represents a monovalent organic group, when two R's are present, the two R's may be the same or different, and they may be bonded to each other to form a cyclic structure; Z and R may be bonded to each other to form a cyclic structure; and n represents an integer of 1 or 2; and the compound capable of generating the organic acid represented by formula (I).